BoxyBot IIIntermediate Presentation

Fin Design, Programmation, Simulation & Testing

Author: Benjamin FankhauserAssistants: A. Crespi, M.Porez

Professor: A.J.Ijspeert

Content Overview

• General Design• Programmation using a CPG• Localization and Control• Fin Design & Testing

– Resonance frequency– Efficiency Estimation

• Simulation

Programmation using a CPG

Programmation using a CPG))sin((

jijijjijii r

iii

rri rrRa

ar )(4

iii

xxi xxXa

ax )(4

)cos( iii x

)cos()(lim ,0 iiiiit

tRXt

[1]

[2]

Localisation and Control

VideosBoxyBotII - Behaviour with proportional controller

BoxyBotII - Behaviour without controller

Fin Design - Resonance Frequency

afr mm

kf

21

3

3

3 4 l

twE

l

IEk

Spring Constant:

Results – Fin AmplitudeFin 1 : 95x40 mm FR1=0.7±0.1 Hz Fin 2 : 95x60 mm FR2=0.6±0.1 Hz

Amplitude vs. Frequency for fin 2

Simulation – Fin Amplitude

Simulated and Real Amplitude vs. Frequency for fin 2 (FR2=0.6±0.1 Hz), Excitation Amplitude 40°, 60° and 80°

Videos

Fin Simulation : Frequence 0.6 Hz - Resonance

Fin Simulation : Frequence 1.2 Hz

Fin Simulation : Frequence 1.8 Hz

Results – Speed and Resonance Frequency

Speed and Amplitude vs. Frequency for fin 2 (FR2=0.6±0.1 Hz), Excitation Amplitude 40°

Results – Speed and Excitation Amplitude

Speed vs. Frequency for fin 2 (FR2=0.6±0.1 Hz)

Simulation and Reality - Speed

Simulated and Real Speed vs. Frequency for fin 2, Excitation Amplitude 60°

BoxyBot Swimming Behaviour

VideosBoxyBotII : Caudal Fin and Body Segment Propulsion

BoxyBot II : Pectoral Fin Propulsion

BoxyBot II : All Fin Propulsion

Efficiency Estimation

v

fASt

Strouhal Number: [3] [4]

Conclusion

• BoxyBotII swims in a controlled manner• Fin Design

– Resonance Frequency FR

– Good Efficiency around FR

– Use only Caudal Fins for Propulsion

• Simulation– Comparable Amplitude

Plot– Model needs Optimizing

Bibliography1. A.Crespi, D.Lachat, A.Pasquier, A.J.Ijspeert: „Controlling swimming and crawling in a sh

robot using a central pattern generator“, BIRG, School of Computer and Communication Science, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, 2005

2. A. Crespi and A.J. Ijspeert. AmphiBot II: „An amphibious snake robot that crawls and swims using a central pattern generator“, in: Proceedings of the 9th International Conference on Climbing and Walking Robots (CLAWAR 2006), 2006.

3. S.Heo, T.Wiguna, H.Ch.Park, N.S.Goo: “Effect of an Artificial Caudal Fin on the Performance of a Biomimetic Fish Robot Propelled by Piezoelectric Actuators”, Journal of Bionic Engineering 4, 151-158, 2007

4. J.J.Rohr, F.E.Fish: “Strouhal numbers and optimization of swimming by odontocete cetaceans”, The Journal of Experimental Biology 207, 1633-1642, 2004